This invention relates generally to tamper-evident seals, and more particularly to wire seals.
Prior art locking seals generally come in two types: strap seals and wire seals. Strap seals generally include a flat, typically plastic or metal strap which is inserted through the hasp of a lock. The strap end is then inserted into the seal body where it cannot be removed. An example of such a strap seal is disclosed in U.S. Pat. No. 5,513,421 issued to Wells. One of the disadvantages of strap seals is that the strap has a relatively large dimension, as compared to a wire. The strap typically is flat and includes a pair of broadly planar surfaces. Such seals cannot be used in locks having hasps of a relatively narrow aperture. Such locks require the use of a seal having a wire or other relatively narrow, elongated member.
Prior art wire seals, however, have suffered from the disadvantage that they require multiple steps to use. For example, one prior art wire seal is disclosed in U.S. Pat. No. 5,402,958 issued to Mahaney. The wire seal disclosed therein first requires the wire to be inserted into an aperture defined in the seal. After this a plug must be rotated in the seal. The use of the seal thus requires two steps: insertion and rotation. Another such example is U.S. Pat. No. 5,762,386 issued to Fuehrer. This patent discloses a tamper resistant seal in which a wire must first be wrapped around an insert. The insert is then inserted into a receptacle from which it cannot be removed. Not only does this require multiple steps, but maintaining the wire around the insert while simultaneously inserting it into the receptacle requires a certain amount of dexterity and coordination.
The desirability can therefore be seen of a self-locking wire seal which is simple to use and which eliminates the multi-step requirements of prior art wire seals.
Accordingly, the present invention provides a self-locking wire seal which can be operated with only a single step. The seal is both easy to use and economical to manufacture and provides all the benefits associated with prior art wire seals.
A self-locking wire seal according to one aspect of the present invention includes a body and a spiral wound wire which has a first end secured to the body. A channel is defined in the body and is sufficiently large to receive a second end of the spiral wound wire. A lock is positioned inside of the body adjacent the channel and is adapted to contact the spiral wound wire when it is inserted in the channel. The lock allows the wire to be inserted but not retracted from the channel.
According to another aspect of the present invention, a self-locking seal includes a body, a flexible, elongated member, and a channel defined in the body. An interior space is also defined in the body and in communication with the channel. A spring is housed in the interior space of the body. The spring includes a sidewall, a base wall, and a flexible arm. The sidewall is oriented generally parallel to the channel while the base wall is oriented generally perpendicular to the channel. The flexible arm is oriented at an angle with respect to the base wall and extends partially into the channel. The base wall includes an aperture in alignment with the channel. When the flexible, elongated member is inserted through the channel and the aperture, it is prevented from being removed from the channel by the flexible arm of the spring.
According to another aspect of the present invention, a self-locking seal includes a body having a plurality of sides. The body includes a first channel and a second channel. The first channel extends out of one of the plurality of sides of the body while the second channel extends through said body from one side to an opposite side of the body. A chamber is also defined in the body and is in communication with the first channel. A slug is provided and is dimensioned to fit within the chamber. A wire is secured to the slug and extends out of the body through the first channel. A spring is housed within the body and extends at least partially into the second channel. The spring is flexible enough to be pushed out of the channel when the wire is inserted into the second channel in a first direction. The spring is also oriented at an angle in the second channel such that the spring grips the wire when the wire is retracted in the second channel in a second direction opposite the first direction.
According to yet another aspect of the invention, a method of sealing an object having an opening includes providing a seal body having a metal wire secured thereto. The metal wire has a free end which is unsecured to the seal body. A channel is defined within the body and a flexible spring is provided within the body. The flexible spring extends at least partially into the channel and is oriented to grip the metal wire when the metal wire moves through the channel in a first direction. The flexible spring flexes out of the way of the metal wire when the wire is moved through a channel in a second direction opposite said first direction. The free end of the metal wire is inserted through the opening in the object and subsequently inserted until the free end moves past the flexible spring.